Don't know if this is the OP first SKS, but I'm pretty sure you're going to enjoy it. Though many of us got them way back when for very little, it's still a center fire, battle proven, semi-auto that uses inexpensive ammo for what, $300? Sounds like you did well, good luck with it!
For what it's worth, my Norinco works well with a Tapco 20 round removable magazine, has to be inserted with the bolt open though. I have a fixed 20 round Chinese star magazine I've never tried, but I've read those work well, too.
The price of the stock 10 round mags have gone up, along with the bayonets. Did people toss them and now want them back? The original 10 round matching number magazine off mine is still in my possession, but I think it should stay with the gun.